Acute tryptophan depletion and self-injurious behavior in aggressive patients and healthy volunteers.
BACKGROUND
An association between serotonin (5-HT) activity and self-injurious (i.e., self-aggressive) behavior across the spectrum of lethality (from self-mutilation through completed suicide) is a well-replicated finding. Studies to date, however, have relied on nonexperimental designs to examine this relationship, limiting the causal inferences that can be drawn about the role of 5-HT in self-aggressive behavior.


OBJECTIVE
Examine the effect of experimentally altered 5-HT activity (via dietary tryptophan depletion) on self-aggressive behavior among adults with and without intermittent explosive disorder (IED). Individuals with a marked history of aggression, such as those with IED, are characterized by compromised 5-HT and heightened risk for self-aggression, making this a population of interest for examining the proposed relations.


METHODS
IED patients (n = 16) and healthy controls (n = 16) received a tryptophan depletion and a placebo drink on separate days at least 1 week apart. Self-aggressive behavior was assessed on both study days using a well-validated laboratory-based behavioral assessment with self-aggression defined as the intensity of shock self-administered.


RESULTS
Tryptophan depletion facilitated selection of more intense shocks, on average, in both groups. Patients with IED were also more self-aggressive overall than healthy volunteers. No IED by drink condition interactions were found.


CONCLUSIONS
Experimentally lowered 5-HT bioavailability enhances overall self-injurious behavior irrespective of aggression history.
McCloskey
Michael S
MS
Department of Psychiatry, University of Chicago, 5841 South Maryland Avenue, MC 3077, Chicago, IL, 60637, USA. mmcclosk@yoda.bsd.uchicago.edu
Ben-Zeev
Dror
D
Lee
Royce
R
Berman
Mitchell E
ME
Coccaro
Emil F
EF
D000284:Administration, Oral; D000328:Adult; D000374:Aggression; D021542:Amino Acids, Neutral / Q000008:administration & dosage*; D001628:Beverages; D002214:Capsules; D016022:Case-Control Studies; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000378:metabolism* / Q000523:psychology*; D004597:Electroshock; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017288:Pain Threshold; D011569:Psychiatric Status Rating Scales; D016728:Self-Injurious Behavior / Q000378:metabolism* / Q000523:psychology*; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000097:blood / Q000172:deficiency*; D055815:Young Adult
D021542:Amino Acids, Neutral; D002214:Capsules; D012701:Serotonin; D014364:Tryptophan